Filter



oct. 11, 193s.

L. W. WILLIAMS -ET AL.

FILTER Filed Aug. 11, 1936 `Z9 "go INVENTOR C` :D -26 24M Z5 Z7 Z5 A ATTORNEYS Patented Oct. ll, 1938 UNITED STATES PATE-NT oFFlc 2,133,004 f mm Lewis W. Williams,

Arnold, Chatham, Improvements, Inc., tion of Delaware 'short mus, um Georxe a. N. J., assignors to Motor- Newark, N. J., a corpora- Appuuon am 11, 193s, sei-m No. 95,33 somma. (Otero- 169) 'This invention relates to filters and more especially to metal ribbon filters of the type disclosed in the patent to R. P. F. Liddell, No. 2,042,537. The filter disclosed in said Liddell 5 patent comprises a helix of metal ribbon having contacting turns, the flltering interstices being provided through the medium of transverse ribs formed on one face of the metal ribbon. The proper curvature is given to the ribbon and the transverse ribs are formed thereon by passing the ribbon between conical pressure rolls, one of which is provided with a series of slots which result in the formation of the ribs.

An object of the present invention is a lter of the type above described having extremely minute filtering interstices whereby it is capable of filtering out the most minute particles.

The minute spacing of the turns of the helix is attained by the use of specially prepared pressure rolls in the operation of shaping the ribbon. One of the pressure rolls is formed with a surface of glass-like smoothness while the other pressure roll is sand-blasted with sand grains of a definite size projected at a predetermined ve- 25 -1ocity. By selection of the size of the sand grains and control of the velocity of projection, the depth of the recesses formed in the pressure roll can be accurately regulated to produce projections on the ribbon ofthe desired height to yield filtering interstices of the desired size. The resulting projections on the ribbon may be made microscopic in size and form filtering interstices of the same order of magnitude.

Other objects, novel features and advantages of this invention will become apparent from the following specication and accompanying drawing, wherein:

Fig. 1 is a plan View of a pair of pressure rolls for forming the metal ribbon of which the filtering element ofthe present invention is composed.

Fig. 2 is a side elevation thereof;

Fig. 3. is a fragmentary perspective view of a filtering element embodying the invention;

L Fig. 4 is an enlarged fragmentary section on the line 4 4 of Fig. 3;

Fig. 5 is a vertical section through a. lter'having a ltering element embodying the invention;

Fig. 6 is a similar view with the filtering ele- 0 ment slightly extendedlfor cleaning; y

Fig. 7 is a section on the line 1- of Fig. 6, and

Fig. 8 is a section on the line 8 8 of Fig. 6. i In Figs. 1 and 2, a pair of pressure rolls are 5 driven by any suitable means (not shown) and between vvthem is passed a wire W which is pressed into a ribbon R and given a predetermined curvature as described in said Liddell patent, No. 2,042,537. The operating face of the roll I0 is provided with minute depressions while the operating face of the roll Il is of glass-like smoothness. The minute depressions in the face of the roll III are produced by projecting against it sand grains of definite size at a predetermined velocity. The sand grains produce microscopic depressions and the depth of the recesses thus formed is regulated by selection of the size of the sand grains and control of the projection velocity. 'Ihe ribbon R is therefore produced with one surface of glass-like smoothness and with its opposite surface having minute ,projections and may be indistinguishable by the human eye and be visible only through the medium of a microscope. 'I'he ribbon R is formed into a helix as described in said Patent No. 2,042,537 and when suitably mounted constitutes a ltering element capable of removing the finest of particles from a liquid. 'I'he minute projections on the one face contact the glass-like surface of the other face,

thereby insuring uniformity of filtration throughu out the entire surface of the filtering element. The provision of one surface of glass-like smoothness prevents any possibility of variation in the ltering interstices throughout the length of the ribbon. u

In Fig. 3, there is shown a fragment of a nltering ,element to illustrate the general subjectmatter of the filtering element and its arrangement while in Fig 4 is illustrated the difference betweenthe two faces of the ribbon R. In Fig. 4, the lower fragment is from the upper portion of a turn of the ribbon R while the upper fragment is from the lower portion of the next turn 'of a ribbon R. The upper surface of the lower which denne the filtering interstices while the o lowerv surface of the upper fragment is of the glass-like smoothness previously mentioned.

InFigs. 5 to 7, 20 is a illteringfelement comprising a helix composed of ribbon produced in accordance with the previously described procedure and having the surface characteristic resulting from such procedure., 'I'he helix 20 is mounted on av frame 2l which consists of two cross metal strips suitably inter-connected. To one end of the frame 2| is ilxed a head 22 against which abuts one end of the helix 20. 'I'he other end of the frame is recessed at 23 and into this recess projects the hub 2l of a cap 25 having a flange 26 overlying the end of the irame, the cap lbeing capable of sliding movement on the frame toward and away from the carp 22. A spider.; or retainer 21 is carded by the ends of the strips which form the trarne 2| s the acts as a guide for the hub 2e. Alsofwithin the recess 23 is a spring 28, one end of which is attachedto the i'ramfand the other end o! which is attached to the cap 2% through thev medium of a yoae 29 and bolt 30. 'I'he illter 10 element is arranged within a casing 2| having an inletl2, the casing being provided with a cap 32 having an outlet 2l communicating with A apertures 25 in the cap 22.

In operation, liquid to be ltered is introduced into the interior thereof from which itis discharged by wayioi the apertures I! through the outlet 34. 4Cleaning ofthe filter is eiiected'by l0 reversirgg the ilow oi liquid; thereby establishing a pressure differential between the interior andi .Y exteriorV o! the iiltering element. 'llhislpressuze' '.dierential causes the cap 25 to move rom the lposition shown in Fig. 5 to the position shown in Fig. 6 and permitting corresponding ,expan- Vsion of the helix withY resulting slight spacing of the turns. The outward ilowoi liquid through the turns washes out any deposit ot filtrate and cleans the lter. As soon as the pressure difier- 86 entiall-betweenV the interstices and the exterior of'the'ilter is removed, the spring 28 returns tlf-e 1 cap 25'Y to its original position, thereby causing the 0f the again to be into contact. The turns remain contact during I normal operation oi the iiltersince the pressure 'exterior oi the filtering element is greater than into thecasing through the inlet I2 andV passes .i inwardly through the interstieesfin the helix 20 Y the pressure within the ltering element and tdifferential tends to move the cap 25towards the cap 22. Y

We claim:

l. A lter comprising a helix of metal ribbon 6 "having contacting turns, one face of said ribbon being smooth and the other face being provided with microscopic projections produced from pressure applied thereto by a sand-blasted surface.

. ribbon being smooth and the other face being .provided with irregularly arranged microscopic projections oi varying height'deiiningminute in- 25 terconnecting tortuous channels of varying depth between adjacent turns from one side o! the helix to the other, a cap for each end oi said helix, andresilient means urging said caps toward each other. .Y n

5. A lter according to claim 4 which said other surface has the reverse characteristics of a sand-blasted surface.

LEWIS w. WILLIAMS. 35 GEORGE A. ARNOLD. 

